This invention relates to a system for providing an improved seal to a conduit having a flat surface and to a novel gasket used in such a system.
There are many applications in which a conduit or fluid flow component has coupling hardware with a flat end surface at which the conduit or component is to be connected to another conduit. Typically, to provide a sealing connection to such a flat coupling hardware in vacuum or high pressure applications, or applications requiring an ultra high purity, a metal O-ring or C-ring is used to provide the sealing engagement. In such coupling hardware, a problem exists in maintaining the sealing ring centered. If the sealing ring is not centered, it interferes with the flow path through the coupling hardware and if it moves after pressure is applied to the coupling hardware to achieve sealing engagement, this action may cause scratching of the sealing surfaces resulting in leaks. In addition, the surfaces against which the sealing ring seals must be machined with a relatively high degree of precision to achieve a good sealing engagement. If the sealing ring could be maintained centered with assurance, the sealing area over which the precision machining must be carried out could be reduced thus reducing the cost of the coupling hardware.
Another problem with coupling hardware having flat sealing surfaces is that it is frequently desirable to make a connection between such a fitting and VCR coupling hardware which has a toroidal bead on an endface to make sealing engagement with the gasket. When a VCR-type conduit has to be connected to a fitting having a flat surface, it is necessary in the present state of the art to provide a transitional fluid connector having one end designed to make sealing engagement with the flat surface of the flat coupling hardware and the other end of the conduit formed with a toroidal bead to connect with a VCR-type conduit. It would be a great convenience to be able to make a direct connection between flat coupling hardware having a flat sealing surface and a VCR-type conduit having a toroidal bead on its endface.
One place where such a sealing system could be used would be in valve fittings. Typically, the coupling hardware on valves are provided with female threads and are designed either with flat sealing surfaces or with toroidal beads to make connection to VCR-type conduits. To save cost, it would be preferable to make the sealing surface of the valve fitting flat rather than with a toroidal bead, but such structure means that the coupling hardware cannot connect directly to a VCR-type fluid conduit in the present state of the art.
Sometimes the fluid system to which the valve must connect does not employ VCR-type coupling hardware and if the available valves to be connected to such a fluid system are provided with a VCR-type coupling hardware, a transitional connector must also be provided between the two systems in this situation. This problem arises because the valves are expensive and it is not economical to keep both valves with both flat coupling hardware and VCR-type coupling hardware in stock.